drm/vc4: Fix bitwise OR versus ternary operator in vc4_plane_mode_set

Clang warns:

drivers/gpu/drm/vc4/vc4_plane.c:901:27: warning: operator '?:' has lower
precedence than '|'; '|' will be evaluated first
[-Wbitwise-conditional-parentheses]
                                fb->format->has_alpha ?
                                ~~~~~~~~~~~~~~~~~~~~~ ^
drivers/gpu/drm/vc4/vc4_plane.c:901:27: note: place parentheses around
the '|' expression to silence this warning
                                fb->format->has_alpha ?
                                ~~~~~~~~~~~~~~~~~~~~~ ^
drivers/gpu/drm/vc4/vc4_plane.c:901:27: note: place parentheses around
the '?:' expression to evaluate it first
                                fb->format->has_alpha ?
                                ~~~~~~~~~~~~~~~~~~~~~~^
1 warning generated.

Add the parentheses as that was clearly intended, otherwise
SCALER5_CTL2_ALPHA_PREMULT won't be added to the list.

Fixes: c54619b ("drm/vc4: Add support for the BCM2711 HVS5")
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Link: ClangBuiltLinux/linux#1150
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20200910171831.4112580-1-natechancellor@gmail.com

drivers/gpu/drm/vc4/vc4_plane.c

@@ -965,8 +965,8 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
 		vc4_dlist_write(vc4_state,
 				VC4_SET_FIELD(state->alpha >> 4,
 					      SCALER5_CTL2_ALPHA) |
-				fb->format->has_alpha ?
-					SCALER5_CTL2_ALPHA_PREMULT : 0 |
+				(fb->format->has_alpha ?
+					SCALER5_CTL2_ALPHA_PREMULT : 0) |
 				(mix_plane_alpha ?
 					SCALER5_CTL2_ALPHA_MIX : 0) |
 				VC4_SET_FIELD(fb->format->has_alpha ?